Hydraulic follow-up system



Dec. 12, 1950 i w. H. NEWELL 2,533,306

HYDRAULIC FOLLOW-UP SYSTEM Original Filed May 5, 1944 2 Sheets-Sheet 2INVENTOR T Wq/nglfNewglb ATTORNEY Patented Dec. l2, 1950 HYDRAULICFOLLOW-U1 SYSTEM William H. Nowell, New York, N. Y., assignor to TheSperry Corporation, a corporation of Dela- Ware Original application May5, 1944, Serial No. 534,330. Divided and this application May 17, 1945,Serial N 0. 594,288

Claims.

This invention relates to automatic gun control systems of the typeresponsive to hydraulic pressures and in particular to a novel andimproved hydraulic follow-up system responsive to a manual controldevice and including a pressure control valve mechanism adapted tocontrol generated pressures and a pressure responsive servomotor foractuating the driving and computing mechanisms.

This application is a division of the copending application of Newell etal., Serial No. 534,330, filed May 5, 1944, for Automatic Gun ControlSystem.

An object of the invention is to provide a valve mechanism of the abovetype having novel and improved details of construction and features ofoperation.

Other and more specific objects will be apparent as the nature of theinvention is more fully disclosed.

In accordance with the present invention a pair of pressure controlvalves are actuated in accordance with the position and rate of movementof the gunners control handle to vary hydraulic pressures in a manner toproduce control pressures correspondin to the desired rates of train andelevation respectively. These control pressures are applied to thepressure responsive servomotors which are adapted to control rate inputlinkages of an automatic computing mechanism. The pressures may also beapplied to precessing force motors which apply precessing forces to agyroscope as more fully set forth in the patent application aboveidentified.

Although the novel features which are believed to be characteristic ofthis invention are pointed out more particularly in the claims appendedhereto, the nature of the invention will be better understood byreferring to the following description, taken in conjunction with theaccompanying drawings in which a specific embodiment thereof has beenset forth for purposes of illustration.

In the drawings:

Fig. 1 is a section through a hydraulic pressure control valve blockembodying the present invention showing the control handle and thehydraulic connections;

Fig. 2 is a side elevation of the manual control handle and supporttherefor;

Fig. 3 is a vertical section through the control handle and supporttaken along the line 33 of Fig. 1;

Fig. 4 is a partial horizontal section taken on line 4- of Fig. 1; and

Fig. 5 is a diagrammatic view of the follow-up system showing thepressure responsive servomotors in section.

Certain specific terms are used herein for convenience in referring tovarious details of the invention. These terms, however, are to be givenan interpretation commensurate with the state of the art.

Pressure control valves Referring to the drawings more in detail, thepressure control valves are shown as mounted in a valve block I51Control handles I55, adapted to be actuated by the gunner, are shown asmounted on a horizontal shaft I00 which is pivoted in a bracket I56 forrotation about a horizontal axis and carries an arm I, Fig. 3, which isattached by a pivoted link 2 to a slidable rod 3 which is located withinthe bracket I56 and carries a pair of collars t which actuate an arm 5carried by a shaft 6. The shaft 6 in turn carries an arm 1 which isconnected by a link 8 to a valve plunger 9 in a manner such that thevalve plunger is shifted from a central position an amount correspondingto the rotational move-- ment of the handles I55 about their horizontalaxis, The position and rate of movement of the valve plunger 9 controlsthe operation of an elevation pressure control valve Ill. The rotationalposition of the handles I55 corresponds to the elevation rates whichcontrol the position of the pressure responsive servomotor to bedescribed later. These rates may also be applied to'an elevationprecessing motor of a gyroscope to cause the gyroscope to precess at acorresponding rate. The position and rate of movement of the plunger 9controls and is a measure of the pressure which is developed by thevalve ID for actuating the pressure responsive servomotor and theelevation precessing motor. The pressures thus developed are controlledprimarily in accordance with the position of the handles I55, but thesepressures are modified somewhat due to the rate of movement of thehandles.

Rotation of the handles l 55 and shaft l 09 about a vertical axis causesthe bracket I56 to rotate and, in turn, to rotate a segment of abevelled gear l2 which, through a bevelled rack l3, actuates a shaft iscarrying an arm l5 which is attached by a link it to a valve plunger l8which controls the operation of the train rate pressure control valve20. The elevation rate pressure control valve I0 and the train ratepressure control valve 20 are similar in construction and are adapted todevelop pressures corresponding to the .justable restriction formedaxial displacement and rate of movement of the valve plungers 9 and i3respectively.

Referring first to the valve H), the block I5! is formed with a valvechamber 25 in which slides a sleeve 26. The plunger 9 slides axiallywithin a bore in the sleeve 25. The sleeve 2.5 is provided with endsurfaces forming with the respective ends of the chamber 25, pressurechambers 27 and 28 respectively. The chamber 2'! is supplied with fluidfrom a constant pressure, P1 through a supply duct 29. The duct 29contains an adby the adjusting screw 34, the end of which enters andpartially closes the duct 29. The chamber 28 contains fluid under apressure which is determined by the position and rate of movement of,the sleeve 26 and which constitutes the elevation rate pressure Pe whichis suppl ed by passag 30 to a duct 3|. The end surfaces of the sleeve 25are recessed to receive compression springs 32 and 33 which are seatedwithin the chambers 21 and 28 respectively and serve normally to holdthe sleeve .26 balanced in its mid-position, in which event the pressurein th chamber 23 will correspond to the pressure within the chamber 2?.Chamber 28 communicates through a passage 653 with an annular chamber 4!formed in the plunger 9. Passages 42 and 33 in the sleeve 26 terminateat the plunger 9 on opposite ends of the chamber 4! so that thesepassages are normally closed by the plunger 9 when the plunger is in thecenter position as shown, but are respectively brought intocommunication with the chamber 28 through. the chamber ll and thepassage 49 when the plunger 9 is shifted in one direction or the otherfrom its center position. The passage 42 communicates with an annularchamber 45 formed around the periphery of the sleeve 25 and the passage63 communicates with an annular chamber 45 sim larly formed in thesleeve 26. The chamber 45 receives fluid under a constant pressure P2which is double the pressure P1 and is supplied through a passage 41 inthe block I51 which communicates with a supply duct 48 receiving fluidunder the pressure P2 from a suitable source. The chamber 46 containsfluid under a low or zero pressure P which may constitute the intakepressure of the pump. The chamber 46 communicates through a passage 49with a return duct 59 which leads. to th supply reservoir of the pump.

The pressure P1 is supplied by a P1 generator valve 55 formed in theblock l! and comprising a chamber having a slide 56 provided with endsurfaces 5'! and 58 forming end chambers 59. and 99 respectively. Theend surface 5'! is .formed with one half of the area of the end surface58 so that when the slid 55 is in balanced position the pressure withinthe chamber 69 will be. half that within the chamber 59.

The chamber 59 is connected to the passage 41 containing fluid underpressure P2 by means of a passa 62. The slide 56 is formed with anannular chamber 63 which communicates through a passage 64 with the duct29 to supply fluid under the pressure Pl thereto, The annular chamber 53communicates with the chamber 69 by means of a passage 55 in the slide.

The slide 58 is provided with a reduced diameter end portion '59terminating at the surface 51 above mentioned and has an annular endsurface ll surrounding the end portion 10. This annular surface 'H formswith an intermediate end wall of the valve chamber an annular chamber12. The annular chamber 12 communicates through a passage 73 with thepassage 49 containing fluid under return pressure P0. The passage l3terminates at the slide 59 adjacent one end of the chamber 63 so that itis normally closed by the slide. A passage 75 communicates from thepassage 62. to; the valve chamber on the opposite end, oi the annularchamber 63 so that when the slide 56 is in its mid position, thepassages 75 and 73 are both closed. The fluid pressures in the two endchambers 59 and 60 are then balanced and, due to the differences in areaof the end surfaces, the pressur P1 is generated at exactly one-half ofthe pressure P2. If the pressure Pi should, however, vary from thisamount, the pressure within the chamber 60 would likewise vary, therebyunbalancing the slide 56. If the pressure in the chamber 60 is reduced,for example, the pressure P2 in the chamber 59 causes the slide 56 tomove upwardly, thereby establishing communication from the passage 75through the. chamber 63 to the passage 65, thereby introducing fluidfrom the passage 15 into the passage 65 and increasing the pressure inthe latter passage. The, pressure will thus be built up until thepressures in the chambers 59 and 69 are again balanced.- at which timethe. slide 5'5 returns to its mid position and cuts off further fluidfrom the'passage 15.

If, on the other hand, the pressure within the chamber 69 increases, theslide 58 will be forced downwardly establishing a communication from thepassage 65 through the chamber 63 to the passage 13, thereby bleedingoif some of the fluid Within the passage 65 into the return duct 50.This will likewise continue until the pressure in the chamber 69 isreduced to P1, at which time a balance is again established. In this wathe pressure in the passage 54 is maintained at exactly one-half of thepressure (P2) in the duct 48.

In the operation of the elevation rate pressure control valve l9,beginning with the valve plunger 9 in the position shown, the pressurein the chamber 28' is exactly balanced against the pressure P1 in thechamber 2 The elevation rate pressure Pe accordingly is the same as P1.If now the gunner rotates the handles about the horizontal aXis forproducing a rate in elevation, the valve plunger 8 will be moved axiallyin one direction or the other. Assuming, for example, that the plunger 9is moved upwardly, the chamber 4| is brought into communication with thepassage 42 and fluid under pressure P2 is supplied through the chamber4| and passage 19 to the chamber 28, thereby increasin the pressure inthe. chamber 28 and disturbing the balance between the chambers 2? and28. This increased pressure in the chamber 28 causes the sleeve 25 tomove upwardly, thereby compressing the spring 32 and reducing thecompression on the spring 33. This increase in pressure in chamber 28causes the sleeve 26,,tc follow the plunger 9 upwardly until the sleevehas again reached a position relative to the plunger 9 at which thepassage 42 is closed 01?. If the sleeve should move past this closingposition, then communication would be established between the chamber 28and the passage 43 which would remove some of the fluid from the chamber28 to the return passage 49 and would correspondingly reduce thepressure on the lower end of the sleeve 26. When a new position of resthas been reached, the pressure within the chamber 28 plus the pressureof the spring 33 will exactly equal the pressure in the chamber 21 plusthe pressure of the spring 32. The upward displacement of the twosprings, however, rep resents a net downward pressure on the sleeve 26proportional to the displacement of the sleeve 26 from its mid-position.This downward pressure of the spring acting on the sleeve 26 isreflected as an increase in hydraulic pressure in the chamber 28 and inthe pressure of the fluid Pa in the passage 39 and in the duct (H whichcommunicates therewith. This increase in hydraulic pressure is thusprimarily proportional to the amount of vertical movement of the plunger9 and the corresponding movement of the sleeve 26.

The restriction formed by the screw 34 in duct 29 restricts the flow offluid from the chamber 2'! and therefore the pressure in chamber 21becomes higher than the normal P1 pressure during upward movement of thesleeve 26. This higher pressure in chamber 21 results in a furtherincreased pressure in the chamber 28 during upward movement of thesleeve 25. The efiect of this transient change of pressure due to rateof movement of the handles I55 is to modify temporarily the generatedpressure in a direction to apply a supplemental force to the pressureresponsive servomotor to thereby overcome initial resistance to movementof the mechanism connected to the servomotor. When the generatedpressure is used to apply processing forces to a gyroscope thetemporarily modified pressure acts to correct the position of thegyroscope. The effect of this modification of the precessing pressure isto aid the gunner in tracking the target when the gyroscope is used tocontrol a line of sight, since it is not necessary for him to set upexcessive precession rates in order to brin the line of sight on thetarget when it has gotten off for any reason. The relative amount bywhich the generated pressure is thus modified by the rate of movement ofthe handles I55 may be varied to suit the operator by adjusting thescrew 34.

Movement of the plunger 9 in a downward direction reverses the abovementioned operation, establishing communication between the chamber 23and the return passage 49 and thereby reduc- 1;

ing the pressure in the chamber 28 to establish a pressure differentialbetween the chambers 2! and 28 which causes the sleeve 26 to follow theplunger 9 downwardly. In this way the pressure within the chamber 28,and within the duct 3| wh ch is supplied thereby, is caused to increaseor decrease from the normal pressure P1 by an amount determined by thedirection, amount and rate of movement of the plunger 9 from its centralposition. The resultant pressure (Pe) established in the duct 3iaccordingly represents the elevation rate (dE) which is to be set intothe automatic computing mechanism and the direction and amount of theprocessing force which is to be applied to the gyroscope.

The construction of the valve 20 is identical with that of the valve ID.The description will accordingly not be repeated. The parts of the valve20 have, however, been given corresponding reference characters with theaddition of a t to indicate that they apply to the tra n rate pressuregenerating valve. The chamber 281E communicates through the passage 3%with a duct 38 which carries fluid under pressure Pt which representsthe train rate (dBs) which is to be set into the automatic computingmechanism and the train precessing force to be applied to the gyroscope.

Rotational movement of the handles I55 and the shaft I about thevertical axis of the bracket Ill) I56 causes a corresponding axialmovement of the plunger I8 which is followed by the sleeve 2623 togenerate the pressure Pt in the chamber 2Bt which varies from thepressure P1 in a direction and by an amount determined by the direction,amount and rate of rotational movement of the bracket I56. This movementcorresponds to the rate of train which the gunner desires to set intothe control apparatus.

Pressure responsive SGT DOmOtOTS Referring now to Fig. 5, the rateamplifier servo block 2| 0 is shown as containing train rate amplifierservo 220, elevation rate amplifier servo 22! and a P1 generator valve222 which is designed to generate a pressure P1 corresponding to thepressure P1 generated by the generator valve of Fig. 1.

Inasmuch as the P1 generator valve 222 is identical in construction withthe P1 generator valve 55, the corresponding parts have been givenidentical reference characters with the addition of a prime and will notbe re-described. Fluid under pressure P2 is supplied to the chamber 59'of the generator valve 222 from the P2 supply duct 43 through a duct 20!and a passage 223. Return fluid at a pressure P0 is fed to the returnduct 53 from the valve chamber l2 through a passage 22 i and a duct 205.Fluid under pressure P1 is supplied from the valve chamber 60' to apassage 225.

The elevation servomotor 22I comprises a chamber formed in the block2H), containing a hollow piston 23!} and a slide 23I which is mountedfor axial movement within the piston 230. Chambers 232 and 233 areformed at the two ends of the piston 23!]. The chamber 232 is suppliedwith fluid at pressure P1 through a passage 234 which communicates withthe passage 225. Chamber 233 is supplied with fluid at a pressurecontrolled by the operation of the slide 23I through a passage 235communicating with an elongated chamber 236 in the piston 23h.

The slide 23I is acted upon at one end by the hydraulic pressure P1 fromthe chamber 232 and at its other end forms a closure for a chamber 231formed within the bore of the piston 230. The slide 23! is acted upon bytwo opposed springs 238 and 233. The spring 238 extends between one endof the slide 23! and a ring 240 attached to the piston 23!! within thechamber 231. The spring 239 extends between the opposite end of theslide 23I and a pin 2M which is mounted in a fixed plate 2 52 forming anend closure for the chamber 232. The pin MI is adjustable for varyingthe tension of the spring 239. The slide 23! is formed with a centralannular chamber 245 which communicates through a passage 246 in thepiston 23!] with the chamber 236 and is thus in communication with theend chamber 233.

Fluid under pressure P2 is supplied through a passage 25!] from apassage 25I, which communicates with the duct 291, to an elongatedchamber 252 formed in the piston 230 and thence to a passage 253 whichterminates adjacent the lower end of the chamber 245 and is normallyclosed by the slide 23 I.

Fluid at the pressure P0 is returned from the valve 22! to the returnduct 235 through a passage 255 in the block 210, which passage isconnected to the slide 231 through a passage 25% in the block 2| 0leading to an elongated chamber 25? in the piston 230, thence through apassage 258 in the piston 23!] which passage terminates adjacent theupper end of; the chamber 245, and is normally closed by the slide 23!.The passages 253 and 268 are so arranged that one or the other isbrought into communication with the chamber 255 when the slide 23! movesaxially from its balanced position.

Fluid under pressure P6 is supplied from duct 3! (Fig. 1) throughpassage 260 in the block ZIU to an elongated chamber 26! in the piston236, thence through a passage 262 in the piston 23!) which communicateswith the chamber 231.

The link 366 which connects to the automatic computing apparatus isconnected to the piston 230 and extends outwardly from the block 2H1.

The speed of response of the piston, 230 to movements of the slide 23!is controlled by an adjusting screw 255 which extends into the passage235 and controls the flow of fluid therethrough. Thus the controllingeffect on the piston 236 of sudden changes in the controlling pressuredue to the rate of movement of the handles I55 may be eliminated to a,large extent by the restricted flow through the passage 235. A stopscrew 266 carried by the piston 230. extends into the chamber 245 tolimit the axial movement of the slide 236 relative to th piston 238.

Assuming that the pressure Pe equals the. pres sure P1, then thepressure within the chamber 23'! will equal the pressure in the chamber232 and the forces on the two ends of the slide 235 will be balanced.The slide will then take a posir tion at which the forces due to thesprings 238 and 236 are also balanced and the piston 2.36 will be in aposition relative to the slide 2,3i such that the passages 2,58 and 253are both closed, as shown in Fig. 5.

If now the pressure Fe is assumed to increase, the pressure in chamber23'! becomes greater than the pressure (P1) in chamber 232 and the slide23! is caused to move downwardly thereby increasing the tension ofspring 238. This down- Ward movement of the slide 23! opens the passage253 to the chamber 245 and allows flu d under pressure P2 to pass from,the. passage 250 through the chamber 245 and the passag 235 to thechamber 233. This increases the pressure in the chamber 233 and causesthe piston 233 to move downwardly. This action continues until thedownward movement of the piston 238 with respect to the slide 23! againcenters the piston with respect to the slide and closes the passage 253.As the piston 23!] thus follows the move" ment of the slide 23!, thetension of the spring 238 is restored to normal. The slide 23! and thepiston 230 move down together, except for the efiect of the restrictionin passage 235 caused by the screw 265, until the tension of the spring239 is reduced by an amount corresponding to the in,- crease in thepressure Fe in chamber 23?. Since the pressure in the chamber 232 andtension of the spring 236 remain at their normal values, the slide 23iand the piston 236 assume a position where the increased effect of thepressure in chamber 23'! tending to move the slide 23! down isneutralized by the reduced effect of the spring 239.

The sleeve 230 accordingly not only follows the movement of the slide23!, but, due to the large area of the end of the piston 23!] ascompared to the area of the ends of the slide 23!, exerts an increasedforce which may be applied by the link 366 to the input of a computingmechanism such as that set forth in the patent application aboveidentified. The ratio of the force exerted by the link 366 to thatexerted upon the slide 23! may be varied as desired by changing therelative, dimensions of the parts. Hence, the piston 23!] may be causedto exert any necessary force upon the link 366 for actuating thecomputing mechanism.

As explained, the movement of the slide 23! and the piston 230 isproportional to the changes in pressure Pe. Hence the position of thelink 366 represents the rate of elevation dE which is to be set into thecomputing mechanism.

It will be noted that the position taken by the link 366 is dependentonly upon the pressure Pa and is not afiected by leakage in thehydraulic system provided the leakage does not change the pressures. Forany static position of the plunger 9 there is an exact correspondingposition for the link 366 which is determined by the spring andhydraulic pressures only, provided of course the hydraulic system hassufiicient capacity to keep the various passages and ducts full at thevarious pressures.

The elements of the train rate servomotor 220 are identical with thoseof the elevation rate servomotor above described and have accordinglybeen given the same referenc characters with the suifix t. Fluid underpressure Pt is supplied to the train rate servomotor from the ductthrough a passage 216 in the block 2!0. This causes a movement of theslide 23 It which is proportional to changes in pressure Pt and acorresponding movement of the piston 230? which actuates the link 355 tointroduce the rate of train dBs into the computing mechanism.

Although specific embodiments of the invention have been shown forpurposes of illustration, it is to be understood that the invention iscapable of various adaptations as will be readily apparent to a personskilled in the art. The invention is only to be limited in accordancewith the scope of the following claims.

What is claimed is:

l. A pressure control valve comprising a valve housing, a sleeve in saidhousing forming fluid chambers at its two ends, spring means balancingsaid sleeve, means supplying fluid at a fixed intermediate pressure toone of said end chambers, a high pressure chamber, a low pressurechamber, a plunger movable in said sleeve and passages adapted toselectively connect said high pressure chamber or said low pressurechamber to the other of said end chambers for causing said sleeve tofollow said plunger and to establish a pressure diiference between saidend chambers to counterbalance the unbalance of the spring pressuresacting on the ends of said sleeve due to movement of said sleeve fromits balanced position and means deriving a control pressure from saidlast chamber.

2. A pressure control valve comprising a valve housing, a sleeve in saidhousing forming fluid chambers at its two ends, springs biasing saidsleeve to a mid-position, means supplying fluid at a fixed intermediatpressure to one of said end chambers, a high pressure chamber and a lowpressure chamber in said sleeve, a plunger extending axially throughsaid sleeve, a passage in said sleeve communicating with the other ofsaid end chambers, a chamber in said plunger communicating with saidpassage, and passages in said sleeve normally closed by said plungercommunicating with said high and low pressure chambers, said passagesbeing adapted to be brought into communication with said plunger chamberand thence with said last end chamber by movement of said plungerrelative to said sleeve to supply said high or low pressure to said lastend chamber to cause said sleeve to follow said plunger, the pressure insaid last end chamber being determined by the unbalance of said springsproduced by and displacement of said sleeve from its mid-position andmeans deriving a control pressure from said last chamber.

3. A pressure control valve comprising a valve housing, a sleeve in saidhousing forming fluid chambers at its two ends, means centrally biasingsaid sleeve, a source of supply of fluid at a fixed intermediatepressure, a passage connecting said source of supply of fluid to one ofsaid end chambers, means restricting the flow of fluid through saidpassage effective to vary the pressure in said end chamber duringmovement of said sleeve, a high pressure chamber, a low pressurechamber, an adjustable plunger movable relative to said sleeve toselectively connect said high pressure chamber or said low pressurechamber to the second of said end chambers and means deriving a controlpressure from said last end chamber.

4. A pressure control valve comprising a valve housing, a sleeve in saidhousing forming fluid chambers at its two ends, means centrally biasingsaid sleeve, a source of supply of fluid at a fixed intermediatepressure, a passage connecting said source of supply of fluid to one ofsaid end cham bers, means restricting the flow of .fluid through saidpassage elfective to vary the pressure in said end chamber duringmovement of said sleeve, a high pressure chamber, a low pressurechamber, an adjustable plunger movable relative to said sleeve, apassage in said sleeve communicating with the other of said endchambers, a chamber in said plunger communicating with said passage, anda pair of passages in said sleeve normally closed by said plunger andcommunicating with said high and low pressure chambers respectively,said passages being adapted to be brought into communication with saidplunger chamber and thence with said last end chamber upon relativemovement between said plunger and said sleeve and means deriving acontrol pressure from said last end chamber.

5. A fluid pressure control valve comprising a source of high pressurefluid, a source of intermediate pressure fluid, a chamber for exhaustfluid, a valve housing, a sleeve in said housing forming fluid chambersat its two ends, means centrally biasing said sleeve, a passageconnecting the source of intermediate pressure to one of said endchambers, means restricting the flow of fluid through said passageeffective to vary the pressure in said end chamber during movement ofsaid sleeve, an adjustable plunger movable relative to said sleeve, aport in said sleeve connected to said source of high pressure, a secondport in said sleeve connected to said chamber for exhaust fluid, and athird port connected to the second of said end chambers, said portsbeing positioned to selectively connect the first or second ports to thethird port upon relative movement between the plunger and the sleevewhereby the sleeve follows the movement of the plunger and the pressuregenerated in said second end chamber is responsive jointly to thepressure in said one end chamber and the biasing force acting on thesleeve due to displacement of the sleeve from its centrally biasedposition and means deriving a control pressure from said last endchamber.

WILLIAM H. NEWELL.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number

